73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: cochese on July 06, 2007, 05:27:01 PM
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hello - i recently joined the site. i just got an 86 c-10 lwb, 305 v-8. i'm trying to get it running well enough to be a relatively dependable daily driver. i'm having an issue right now with the truck wanting to stall when i start it up.
background info - since the ruck is an 86, the original carb had a bunch some extra emissions stuff. the previous owner replaced the carb with another q-jet without some of the emissions sensors,etc. - for one, there is a dangling wire that i think is from the coolant temp. sensor. i'm wanting to know if this will lead to any problems or performance losses. if so, what options do i have other than trying to find the carb that originally came with the truck. i would consider an aftermarket carb.
now on to my current problem -
when i start the truck, i let it warm up (how long should this be?) it idles fine in fast idle. then i hit the throttle lightly to disengage the fast idle. when i do that, the idle speed goes down, but then starts to stumble a bit. when i put it into reverse (most noticeable in reverse) , the truck starts idling down until it eventually dies unless i give it some throttle. if i get moving right after i shift, i can get moving. same if i get into drive quickly. when i'm at a light, it stumbles but won't die (yet). however, sometimes i don't have this problem - idles fine at lights, no stumbling. one thing that i have noticed, is that the oil pressure gauge jumps around as it stumbles. i don't know if one thing has anything to do with the other, but it seems wierd that the oil pressure drops as the idle goes down - ???
i hope this isn't too long. i'm just looking for suggestions. it may be that i need a carb rebuild, or new carb. recently had it at a mechanic who said the idle was high and adjusted it down some. seems like it started happening around the same time. any help is much appreciated. thanks.
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Welcome to the board from New Hampshire.
If it started happening after he adjusted the idle down I would turn it back up a some and see if it continues before anything else.
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thanks for the quick response. i tried adjusting it back up as suggested, but the idle still stumbles/fluctuates and as it does - the oil pressure gauge goes down and back up. could it be something dealing with the sending unit? thanks.
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sounds an awful lot like maybe vacuum leaks or the carb is just plain shot and needs a rebuild.
The oil pressure will naturally go up or down with the rpms especially on a well worn engine.
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My 86 2500 with a 350 the choke runs through the oil pressure sending unit. I had problem with the sending unit not working and it made the choke in-op too. I by passed it in the wiring and put in after market gages.